join vs sovietise

join is a noun but sovietise is not a noun.

Word	Noun	Adjective	Verb	Adverb
join	Yes	No	Yes	No
sovietise	No	No	Yes	No

As verbs, sovietise is a hyponym of join; that is, sovietise is a word with a more specific, narrower meaning than join:

join (noun)	sovietise (noun)
a set containing all and only the members of two or more given sets
the shape or manner in which things come together and a connection is made

join (verb)	sovietise (verb)
make contact or come together	model a country's social, political, and economic structure on the Soviet Union
cause to become joined or linked	bring under Soviet control, of a country
become part of; become a member of a group or organization
come into the company of
be or become joined or united or linked